Bug 5175: Add missing Title + Subtitle to 3 styles

- Britle:
    Supplement propgroups and CSS to display and customize Title,
    Subtitle, Pagetitle.
- Negatives:
    Supplement Page::print to add call to print_global_title() and
    print_global_subtitle().
    Supplement propgroups and CSS to display and customize Title
    and Subtitle.
- Skittlish Dreams:
    Supplement Page::print to add call to print_global_subtitle().
    Supplement propgroups and CSS to display and customize Title
    and Subtitle.
(Bug 1706) add snakes and boxes style
-- add style files
-- add preview pic
(Bug 1706) add snakes and boxes style
-- fix display of comments
-- remove trailing spaces and extra blank lines
(Bug 1706) add snakes and boxes style
-- add other themes w/ previews
Merge pull request #537 from meludame/bug5175/AddMissingSubtitles

Bug 5175: Add missing Title + Subtitle to 3 styles
Merge pull request #549 from ninetyd/bug1706/style_snakes_and_boxes

(Bug 1706) add snakes and boxes style